Process for recovering manganese values



March 20, 1934. w. BRADLEY PROCESS FOR RECOVERING MANGANESE VALUES Filed Dec. 13, 1926 2 Sheets-Shea?I l QUE/VCH/NG m M sc a 0, GG WN@ TUY owe i www0/WH SYSTEM MMO/VIH MHA/GANESE 7 (2x/OES 7C March 20, 1934. w. BRADLEY PROCESS FOR RECOVERING MANGANESE VALUES Filed Dec. l5. 1926 2 Sheets-Sheet 2 www AJM.

Patented Mar. 20, 1934 PATENT OFFICE PROCESS FOR RECOVERDG MANGANESE VALUE YWilson Bradley, Deerwood, Minn., assignor to Bradley-Fitch Company, Duluth, Minn., .a corporation of Minnesota.

Application December 13, 1926, Serial No. 154,369

8 Claims.

This invention relates generally to the recovery of manganese values from ore and the like and in particular to a commercially practicable process and apparatus employing the principle of leaching manganous oxide from reduced material by a salt solution such, for example, as disclosed in the co-pending application of N. Arthur Laury, Serial No. 46,739, filed July 29, 192,5, corresponding to British Patent No. 284,098 of March 1, 1927.

The process of said application consists of roasting and reducing the material to form manganous oxide, extracting manganous oxide by a solution, preferably ammonium sulphate, under conditions which release ammonia and form manganous sulphate, from which manganese is recovered preferably by precipitation with ammonia in order to regenerate the ammonium sulphate solution.

Said application states that it is desirable to convert all the ammonium sulphate into manganous sulphate so that there is no excess leaching salt in the resulting leach liquor. Under such conditions there is danger of precipitating some of the manganese which has already gone into solulion and, furthermore, it is difiicult using such small concentration of ammonium sulphate to extract al1 the manganous oxide from the ore.

The above named application also describes the precipitation of the manganese as manganous hydroxide. This substance is soluble in an excess of ammonium sulphate. Such solubility is advantageous in the extraction step of the process and disadvantageous in the precipitating step. As the precipitation by ammonia proceeds there is an increase in the concentration of ammonium sulphate, which increase operates against complete precipitation. The present invention overcomes this difliculty and insures complete precipitation when desired.

One object of the present invention is to reduce material containing oxides of both iron and manganese to render the manganese content capable of being leached from the material to form a soluble manganese compound.

It is one object of the present invention to provide an excess of leaching agent during the extraction in order to increase the extracting power of the leach liquor and to remove substantially all the manganous oxide from the reduced ore.

Another object is to provide a process and apparatus for leaching, precipitating and washing the insolubles of the process, so that a maximum yield of manganese can be obtained with a minimum amount of lost liquor and with the employment of a minimum amount of wash water.

Still another object of the invention is to provide a method for the complete precipitation of the manganese from the solution in spite of the fact that the excess leaching salt tends to hold the manganous material in solution.

A particular object of the invention is to oxidize the manganous compounds to form a product which is less soluble in the leachingr salt and which can be more readily washed free from impurities.

In the drawings Fig. 1 is a diagrammatic representation of the steps of the process; and

Fig. 2 is a diagrammatic illustration of the apparatus employed including the countercurrent systems for washing the insolubles.

The following description and explanation of the process is based upon the use of ammonium sulphate as the leaching liquor, but it is to be understood that the process is vnot necessarily limited to such salt, nor are the steps of the process necessarily limited to the disclosure in the drawings. It is also to be understood that the carrier solution may contain any salt or other solvent substance characterized by an ability to convert manganous oxide into a soluble manganous salt simultaneously forming a product which normally precipitates manganese from said manganous salt solution, except in the presence of an excess of the carrier solution, or which precipitates manganese compounds after oxidation of its manganous form.

The ore for which the following process is specially adapted is one containing silica, hema tite, limonite, magnetite, psilomelane and pyrolusite, analyzing in part:

Manganese 19.32%

Iron 24.34% Silica 25.07% Calcium Trace col next quenched, preferably by a leaching solution, using the heat of the ore to raise the temperature of the solution to from degrees centigrade to its boiling point, which may or may not effect evaporation. The quenching takes place in a closed system indicated at 13 in communication with an ammonia system 14 by means of line 15. During the quenching and subsequent thereto, the leach liquor, such as the ammonium sulphate, acts upon the manganous oxide forming manganous sulphate and setting free ammonia which is expelled by the heat.

In order `to facilitate digestion of the manganous oxide, both as to time and eiciency, the quenched ore is wet ground in leaching liquor. By this method the size of the particles is reduced to say about eighty mesh. Initial fine grinding of the ore is thus dispensed with, minimizing danger of reoxidization of the reduced ore and loss of ore by escape of dust. The grinding may be accomplished in a mill 16 preferably connected into the ammonia system by a conduit 17. However, in order to minimize the escape of ammonia. during grinding, this operation may be carried out cold, thus retarding the chemical reaction, and retaining any ammonia whichvmay be formed during grinding.

The preceding operations are, in part, digestive in character, but only incidentally so. The main process of digestion is desirably carried out in two stages, using about ten parts of leach solution to one part of ore. Initially, a ten per cent solution of ammonium sulphate is employed. It is necessary to state that this part of the process is not what might be termed a batch process, because there is an overlapping or crossing of products from these two stages of digestion. The general purpose is to treat partially digested ore with fresh ammonium sulphate as one step, and to treat the fresh ore from the mill with partially spent ammonium sulphate liquor as the other step.

Accordingly, the fresh ground ore from the mill 16 is digested as indicated at 18. Partially spent ammonium sulphate liquor from a suitable supply 19 is employed and the temperature in the digestor is maintained at 95 degrees or more, air being excluded. Using a temperature below boiling prevents large amounts of steam leaving the digestion vessel with the ammonia, thus giving a drier gas and preserving liquid in the vessel to maintain dilution of the chemical ingredients. Live steam is preferably employed to agitate the liquor and to sweep out the ammonia through a conduit 20 into the ammonia system 14. The following reaction represents the changes that occur:-

As the above reaction takes place the ammonium sulphate concentration decreases and the manganous sulphate increases. When the solution contains substantially equal molecular amounts of both salts, it is removed from the ore and reserved for the precipitation step indicated at 21. While it is not necessary that the excess ammonium sulphate correspond to this ratio, it has been found that a heavier precipitate results with these proportions for the amount of ammonia used.

The ore, now partially digested, is treated at 22 with fresh ammonium sulphate from a supply 23.

This may be a new solution or a regenerated solution, as will appear hereinafter. This stage of the digestion is carried out under the same conditions as described above for the first stage 18, and continues until substantially all the manganous oxide is extracted. The partially spent liquor resulting from this final digestion of the ore is then removed and forms the supply 19 to be used for the next leaching operation on fresh ore.

The undissolved portion of the ore is transferred to a, washing system indicated at 24 in order to remove therefrom the adhering liquor containing both manganous sulphate and ammonium sulphate. The washings containing both manganese sulphate and ammonium sulphate may be used at several places in the process. They may provide the solution in which the ore is quenched, orl the washings may be concentrated and added to the leach liquor.

The spent leaching liquid which has been mentioned as reserved for the precipitating step 21 is cooled to about 50 degrees centigrade, which temperature has been found preferable for securing a rapidly settling form of manganese precipitate upon treatment with ammonia and air. However, it may be precipitated even at 80 degrees centigrade. The ammonia may be added either in aqueous solution or as a gas, or both, it being obtained from the ammonia system 14. It has been found that a slight excess of ammonia is desirable in order to reduce undesirable substances in the precipitate. The precipitation is represented by the following reactionszbut when oxidized the resulting MnOOH is insoluble.

Since there is ammonium sulphate present in excess prior to precipitation by ammonia, and since more ammonium sulphate is formed during the precipitation, the manganese cannot be completely precipitated by ammonia alone. This is because it is a characteristic of ammonium sulphate that it holds the manganous compound in solution against complete precipitation by ammonia. Upon separation of the manganese precipitated by ammonia in the absence of oxygen and the supernatent liquor, it will be found that a considerable portion of manganese remains dissolved in the liquor. This manganese contaminates the regenerated ammonium sulphate and lowers the efficiency of recovery. It is well known that an ammoniacal solution of a manganous salt is readily oxidized by air, effecting precipitation of the manganese in a more highly oxidized form than corresponds to the manganous hydroxide first precipitated by the ammonia. It has been found that if air is introduced into the leach liquor during the precipitation with ammonia, the precipitation is complete and the precipitate contains less impurities than when no air is used. For example, I have found that the use of an excess of ammonia and of air in the precipitation gives a product which can be easily washed to have a sulphur content as low as 0.5%. If an excess of ammonia is not employed, the precipitate is difficult to wash and the sulphur content may be as high as 5%. The oxygen of the air destroys all the manganous hydroxide by converting it to a manganic hydrate which is insoluble in ammonium sulphate. Thus a complete precipitation of manganese results. A simultaneous introduction of ammonia and of air to using it for leaching purposes, thus to insure complete removal of manganese. In other words,

lthe impregnated liquor from the digestion may be treated with ammonia in the absence of oxygen to precipitate a portion of the manganese as manganous hydroxide, and the filtrate from this step may be then oxidized to effect precipitation of a whole or a part of the remainder as manganic hydroxide,

From the foregoing it will be seen that upon precipitation of. manganese with oxidation as above described, the ammonium sulphate originally employed is regenerated for further use,.

free from manganese. Without the oxidation, precipitation can. be effected, but not completely, so that the regenerated 4ammonium sulphate will carry a quantity of manganous salt back to the digestion apparatus. Obviously, this is an ineiiicient procedure which is'entirely remedied by the simple use of oxygen in the precipitation.

The regenerated leaching salt is separated from the precipitated manganese by a suitable separation process indicated at 25. The liquor is preferably used to replenish the supply 23 and the precipitate is treatedv in a Washing system indicated at 26. The Washings may be concentrated for addition to the ammonium sulphate supply at 23. The manganese precipitate after washing is preferably thickened, asby the use of a continuous filtration indicated at-2'7, and then subsequently dried as at 28.

The chemistry of the process is dependent in part upon the fact that manganous sulphate in the presence of a sufficient excess of ammonium sulphate is not precipitated by ammonia. The removal of ammonia during the digestion process readily eliminates danger of precipitating the manganese already dissolved. In order, however,

to produce the interaction of ammonium sulphate with the manganous oxide at a commercial efficiency and to insure a practically rcomplete digestion of theiore, there must be at all times an excess of ammonium sulphate in the leaching solution. If air is not used during precipitation with ammonia, the excess ammonium sulphate can not be too great, for it willprevent precipitation of the hydroxide in the later steps. If air is used, the excess ammonium-sulphate will not prevent precipitation, but it will increase the impurities in the insoluble manganese, and add to the diiculty of washing. Sulphur is the primary impurity to be avoided. The physical form of the precipitate to a large extent controls the occluded impurities. It has been found that a 1 to l molecular ratio of` manganese sulphate to ammonium sulphate in the final liquor is a satisfactory ratio for securing a precipitate containing a satisfactorily low impurity content. iThis ratioacorresponds to a solution of assuming, of course, that such a double salt exists.

If, for any reason, the oxidation of regenerated liquor has been incomplete, that portion of the manganous content which remains dissolved will be returned into the digestion apparatus and will later appear in a subsequent precipitation. Thus there will be no loss. As an incidentthen to the possibly incomplete precipitation of manganese, the invention contemplates digestion initially with a mixture which may or may not contain manganous sulphate along with the ammonium sulphate. It is essential for eiiicient, complete digestion, however, that sufficient ammonium sulphate be present to provide an excess at the end of the digestion,and the excess is preferably ,one molecular part of ammonium sulphate for each molecular part of manganous sulphate in the solution. This ratio existing at the end of the process will, of course, also be true at every stage of the digestion. The excess insures that the leach liquor has the proper digestive power and has also a retentive power to prevent precipitation of manganese by the alkalinity existing and created during the digestion. Because of the resort to oxidation to effect` a more complete removal of the manganese from the extracting liquor, an excess of the leaching salt can be employed to make use of its advantageous property of digestion, with an attendant elimination of its disadvantageous property retarding precipitation of manganous hydroxide by ammonia alone. It should be pointed out, however, that the use of oxidation during the precipitation is not an essential feature of the process at each instance of operation. It may be used only occasionally, and when so used it tends to clear the regenerated leaching salt solution from any manganese which it might otherwise carry.

Various forms of apparatus may be employed to use the above described process. Hereinafter follows a description of eicient means which is economical of heat and of material for the process. As carried out in this apparatus, yvarious modifications of the described process will be observed. However, these are but commercially practicable modifications of the principles above set forth.

`The apparatus comprises a reducing furnace 30, preferably of the multi-hearth type. A chute represented at 3l connects the furnace to quenching means in the form of a chamber 32 from which the ore is fed out, along with the quenching liquid, into a wet grinding mill 33. The ground material from the mill then enters a classifier 34 through which passes partially exhausted leach liquor on its Way to the quenching chamber 32. The classifier, the mill and the quenching chamber together comprises a closed circuit, sealed to prevent the ingress of oxygen and the egress of ammonia. There is a passageway 35 for carrying the overflow from the classifier into the quenching chamber, feeding means 36 between the chamber 32 and the mill, and a connection 37 from the mill to the classifier. An ammonia conduit 38 connects this closed system into the ammonia system.

The mixed ore and solution, hereinafter referred to as pulp, are moved .by pump 39 to a digester 40 having preferably a conical bottom 4l, a steam inlet 42, a heating coil 43, and an agitator 44. Digestion with heat and agitation is carried out for about an hour, steam, preferably superheated, being injected into the mass to maintain the temperature and to sweep out the ammonia which is formed. The ammonia and water vapor are carried off in a conduit 45. The ammonia and the vapor in the two conduits 38 and enter a heat exchanger 46 wherein the water vapor is condensedv by a i'low of coolant at In the present apparatus this liquor from one digestion step which is flowing into the quenching and grinding system above described. 'I'he ammonia laden condensate from the heat exchanger 46 passes off through line 47, and the gaseous ammonia is carried away by a conduit 48 to a suction pump 49 which keeps the ammonia in circulation as will later be described.

The pulp from the digester ows into a thickener 50 from which the ore may ow continuously to a second digester 51. The clear solution from the thickener 50 flows in a supply line 52 to a series of chambers comprising in the present instance four similar closed tanks connected in parallel by various valved inlets and outlets. The tanks are designated 53, 54, 55 and 56. 'Ihe leach solution entering the tank series is suiciently exhausted for the precipitation step. For this purpose the liquid is collected in one or more of the tanks as necessity may require.

The digester 51 discharges insoluble tailings, which are of course the undigested part of the pulp. It also discharges ammonia gas, water vapor, and partly exhausted leaching solution. 'I'he gas and vapor discharge through a conduit 57 leading to a second heat exchanger 58 cooled to about 180 F. by a supply of regenerated leach liquor which enters digester 51 by supply line 59. The two heat exchangers 46 and 58 are connected in parallel on the ammonia side, so as to mix their condensates in line 47, and to merge their discharged ammonia gas in the line 48 leading to the pump 49.

'I'he tailings and the leaching solution from the digester 51 enter a separating and washing system comprising six thickeners 60, 61, 62, 63, 64 and 65. This series employs the countercurrent principle of washing, receiving ore tailings and solution in the first thickener 60, and receiving Water in the last thickener 65. 'I'he partially exhausted leach solution and the wash water pass out together from the first thickener 60 by means of supply line 66 through heat exchanger 46 and by line 67 into the quenching and grinding system, via classifier 34.

The precipitation of the manganese is effected by oxidation and ammonia treatment of the solution collected in the series of 'tanks 53 to 56. These tanks are interconnected by a common ammonia conduit 68 which leads to the suction side of the pump 49. Each tank has temperature coils (not shown) so that the solutions therein may be heated or cooled as' desired. The tanks are also provided with air inlet connections (not shown) by means of which air may be admitted to sweep out into line 68 any ammonia which may be released on heating the solution. This air in the ammonia system usually provides the oxygenvnecessary for the precipitation. However, in order to insure a suiciency of oxygen an air inlet valve 69 is placed on the suction side of the ammonia pump 49 to be used as required.

The solution reserved in the tank series 53 to 56 is forced by means such as pump 70 through a pipe line 71 to a precipitation apparatus. In the present instance this comprises two similar bubble-cap type towers 72 and 73, which effect a counter-current flow of the solution and of an ammonia gas and air mixture. The two towers are connected at their top ends to the line 71 which supplies the liquid containing the manganese to be precipitated. Each tower receives a supply of ammonia and air at its bottom end which gases bubble up through the down-flowing solution. The ammonia and air for the tower 72 are supplied directly by the pump 49. The mixture of gases is passed through the tower 72 in excess of the requirements of the solution owing down through the tower, in order that the excess may enter tower 73 through conduit 74 in quantity insuflicient for the requirements of the solution flowing in tower 73. .Thus all the ammonia will be absorbed in tower 73 and the excess air, or the nitrogen left from the air, is allowed to escape through the vent pipe 75. Of course, the rates of material flow are controlled to effect this complete absorption of ammonia.

Since tower 72 discharges completely treated liquor, and tower 73 discharges ncompletely treated liquor, the emergent liquids are kept apart. This is accomplished by connecting each tower separately into each of the tanks. 'I'he lines 76 and 77 represent the respective discharge systems for the towers 72 and 73.

The construction and operation of this system is such that the amountV of ammonia gas employed is less than the chemical equivalent required by the manganese in process. Theoretically, the ammonia liberated in the digestion is held in reserve for the precipitation step, and the quantity liberated is the quantity required, neglecting that excess which is desirable. Actually, itis not held in reserve, except insofar as it is held in the ammonia circulating system, being transmitted from the digesters to the towers wherein it is absorbed. In other words, during the period when it is being theoretically held in reserve for the material from the digestion in which it was liberated, it is beingemployed in the precipitation of previously digested ore. This arrangement of the process and apparatus and the utilization of the ammonia permits dispensing with a large ammonia storage vspace which would otherwise be required. The

reduction in size of the ammonia system thus minimizes the possibility of leaks and the consequent loss of ammonia, as well as the human hazard accompanying the storage and use of large quantities of ammonia.

The operating steps of the precipitation may be carried out in a variety of waysdepending to some extent upon the way in which the tanks and towers are interconnected. The following operation is preferred for the apparatus described. At least three tanks are required, but four are shown, and as many more may be connected in the series as is desired. .For example, it may be assumed that tank 53 holds the solution from the digestion, supplied by the line 52. Tank 54 may hold liquid flowing from tower 72, which liquid will contain manganese that is completely precipitated because of the excess of ammonia employed in the tower- 72. Tank 55 may contain liquid discharged from tower 73. It will contain incompletely precipitated manganese because of the insuflicicncy of ammonia used in tower 73. Tank 56 may be employed for any of these solutions as is required. Of the liquid which flows through the excess ammonia tower 72, it is desirable that a portion should have already passed through tower 73. Thus in feeding the towers by the present apparatus, the pump 70 may draw controlled portions (adjusted by the outlet valves) from the tanks 53 and 55. The liquid in these two tanks, prior to passage through the towers, is cooled to 120 -F. (50 C.) in order to meet the best precipitating conditions. The discharge from tower 73 is preferably returned into the tank 55 or 56 as desired, and fresh solution from line 52 may be mixed with it if deemed necessary. Such a mixed solution may be used in feeding the towers, thus to eliminate drawing simultaneously from two tanks as above men--y tioned.

The discharge from tower 72 is not admixed with other liquid. Under the best conditions `of operation it contains precipitated manganese hydroxide, ammonium sulphate and vexcess ammonia. At this point it is heated in tank 54 to release the ammonia, which is then swept out as aforesaid by air. The liquid carrying precipitate thus freed from the excess ammonia is then drawn off by line 78 to a. separating and washing A system. v

The washing system employed is th'e countercurrent type similar to that above described for washing the tailings. It comprises the thickeners 79, 80, 8l, 82 and 83, and also a continuous lter 84 for concentrating the precipitated manganese to a paste prior to drying. Wash water enters the last thickener 83 and flows against the manganese precipitate and toward the first thickener 79 wherein it mixes with the regenerated ammonium sulphate. The regenerated leach liquor' is forced by pump 85, drawing also, if desired, from the thickener 80, into line 86 leading through heat exchanger 58, and thence by line 59 to digester 5l as hereinbefore explained.

The apparatus so far described is complete as to the main process and includes means for the cyclic use of the leachsolution and of the arnmonia. Air, water, steam and ore are the only materials introduced. The excess air escapes through tower 73 via exit 75. Some water is withdrawn with the wet ore tailings and the wet manganese paste. The rest of the water passes oi as a condensate with some dissolved ammonia in the line 47 yleading from the two heat exchangers 46 and 58. In order to recover the ammonia content, this condensate is forced by a pump 87 to a recovery tower 88, which is preferably of the bubble-cap type similar to the ammonia towers. The condensate flows downwardly against a jet of steam which strips the ammonia from its solution, permitting the tower to discharge steam and ammonia gas at the top, and water at the bottom. The gas and vapor discharge returns to the ammonia system through a conduit 89, thereby joining the vapors and gases from digester 51. The excess water is discharged at 90, and it may be employed as wash water, thus to save any slight amount of ammonia which it might contain. 1

In operation of this apparatus various changes may be made from the exemplary procedure given. Likewise, the apparatus may be varied. It is to be noted that there is a high degree of efliciency in materials employed and in heat consumed. This results largely from the cyclic operations de'- `scribed. Portions of the apparatus may be operated intermittently for batches, and other protions for continuous flow at various times. 'I'his is of course dictated by the exigencies of present conditions. The various thickeners and tanks provide large reserve mediums for the material in the various stages of the process. 'I'hus it is easy to eect an eicient operation in any manner desired. The arrangement permits various parts of the apparatus to be temporarily idle for repairs or replacements without the necessity of a complete shut down.

It is of course to be understood that the apparatus may be used for leaching processes on ores other than manganese, and that it is particularly adapted for minerals which are characterized by higher and lower oxides, the one oxide being soluble under conditions which render the other insoluble.

I claim:

1. In a process for lrecovering manganese values from 'material containing manganous oxide, the stepsof digesting the material with a solution containing ammonium sulphate of sulcient strength to contain at least one molecular part of ammonium sulphate to each molecular part of manganous sulphate present in the solution at any stage of the digestion, and removing resulting ammonia simultaneously with the digestion of the material.

2. In a process for recovering manganese values from material containing manganous oxide, the steps of digesting the material with a solution containing suiiicient ammonium sulphate to convert substantially all the manganous oxide in the material to manganous sulphate and to provide substantially one molecular part of ammonium sulphate for each -molecular part of manganous sulphate present in the solution at the end of the digestion, and removing resulting ammonia simultaneously with the digestion of the material.

3. In a process for recovering manganese values from vmaterial containing manganous oxide, the steps of digesting the material with a solution containing manganous sulphate and sufllcient ammonium sulphate to convert substantially all the manganous oxide in the material to manganous sulphate and to provide substantially one molecular part of ammonium sulphate for each molecular part of manganous sulphate present in the solution at the end of digestion, and removing resulting ammonia simultaneously with the digestion of the material.

4. In a process for recovering manganese values from material containing manganous oxide, the steps of digesting the material with a solution containing suiiicient ammonium sulphate to convert substantially all the manganous oxide in the material to manganous sulphate and to leave a substantial excess of ammonium sulphate at the end of the digestion, and removing resulting ammonia simultaneously with the digestion of the material.

5. In a process for recovering manganese values from material containing manganous oxide, the steps of digesting the material with a solution containing an ammonium salt capable of forming a soluble manganous salt with manganous oxide, which solution contains sufficient ammonium salt to supply at least one molecular part of such salt to one molecular part of the manganous salt at any stage of the digestion, and removing resulting ammonia simultaneously with the digestion of the material.

6. In a process for recovering manganese values from material containing manganous oxide, the steps of digesting the material with a solution containing an ammonium salt capable of forming a soluble manganous salt with manganous oxide, which solution contains suicient ammonium salt to convert substantially all the manganous oxide in the material to manganous salt and to provide substantially one molecular part of the ammonium salt for each molecular part of the manganous salt present in the solution at the end of the digestion, and removing resulting ammonia simultaneously with the digestion of the material.

7. The process of winning manganese values from material containing manganous oxide which comprises wet grinding the material in a solution containing ammonium sulphate, 'digesting f the ground material under the influence of heat in a solution containing an excess of ammonium sulphate over that theoretically required to convert all the manganous oxide to manganous sulphate, removing ammonia released during the' grinding and digesting steps, and recovering manganese values from the solution.

8. The process of winning manganese values from material containing manganese compound which comprises heating the material, Ysimultaneously reducing the manganese content to form 2o 'i e ing ammoniareleased during the quenching,

grinding and digesting steps, and precipitating manganese values from the solution by ammonia.

WILSON BRADLEY. 

